Chronic
Essay title: Chronic
Marijuana is the most commonly used illicit drug in the United States. A dry, shredded green/brown mix of flowers, stems, seeds, and leaves of the hemp plant Cannabis sativa, it usually is smoked as a cigarette (joint, nail), or in a pipe (bong). It also is smoked in blunts, which are cigars that have been emptied of tobacco and refilled with marijuana, often in combination with another drug. Use also might include mixing marijuana in food or brewing it as a tea. As a more concentrated, resinous form it is called hashish and, as a sticky black liquid, hash oil. Marijuana smoke has a pungent and distinctive, usually sweet-and-sour odor. There are countless street terms for marijuana including pot, herb, weed, grass, widow, ganja, and hash, as well as terms derived from trademarked varieties of cannabis, such as, Northern Lights®, Fruity Juice®, Afghani #1®, and a number of Skunk varieties.
The main active chemical in marijuana is THC (delta-9-tetrahydrocannabinol). The membranes of certain nerve cells in the brain contain protein receptors that bind to THC. Once securely in place, THC kicks off a series of cellular reactions that ultimately lead to the high that users experience when they smoke marijuana.
Extent of Use
There were an estimated 2.6 million new marijuana users in 2001. This number is similar to the numbers of new users each year since 1995, but above the number in 1990 (1.6 million). In 2002, over 14 million Americans age 12 and older used marijuana at least once in the month prior to being surveyed, and 12.2 percent of past year marijuana users used marijuana on 300 or more days in the past 12 months. This translates into 3.1 million people using marijuana on a daily or almost daily basis over a 12-month period(1).
The percentage of youth age 12 to 17 who had ever used marijuana declined slightly from 2001 to 2002 (21.9 to 20.6 percent). Among adults age 18 to 25, the rate increased slightly from 53.0 percent to 53.8 percent in 2002. The percentage of young adults age 18 to 25 who had ever used marijuana was 5.1 percent in 1965, but increased steadily to 54.4 percent in 1982. Although the rate for young adults declined somewhat from 1982 to 1993, it did not drop below 43 percent and actually increased to 53.8 percent by 2002(1).
Forty-two percent of youth age 12 or 13 and 24.1 percent age 16 or 17 perceived smoking marijuana once a month as a great risk. Slightly more than half of youth age 12 to 17 indicated that it would be fairly or very easy to obtain marijuana, but only 26.0 percent of 12- or 13-year-olds indicated the same thing. However, 79.0 percent of those age 16 or 17 indicated that it would be fairly or very easy to obtain marijuana(1).
Prevalence of lifetime, past year, and past month marijuana use declined among students in 8th, 10th, and 12th grades in 2003. However, the declines in 12-month prevalence reached statistical significance only in 8th-graders; past year use has declined by nearly one-third since 1996(2). All three grades showed an increase in perceived risk for regular marijuana use. This finding represents a welcome turnaround in this perception, which has been in decline in all grades over the past 1 or 2 years(3).
In 2002, marijuana was the third most commonly abused drug mentioned in drug-related hospital emergency department (ED) visits in the continental United States. Marijuana mentions rose significantly (24%) from 2000 to 2002, but showed no significant increase since 2001. Taking changes in population into account, marijuana mentions increased 139 percent from 1995 to 2002(4).
Effects on the Brain
Scientists have learned a great deal about how THC acts in the brain to produce its many effects. When someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to organs throughout the body, including the brain.
In the brain, THC connects to specific sites called cannabinoid receptors on nerve cells and influences the activity of those cells. Some